Preface ix
1. A medium-wave receiver 1
2. An audio-frequency amplifier 4
3. A medium-wave receiver using a ferrite-rod aerial 9
4. A simple electronic organ 12
5. Experiments with the NE555 timer 17
6. A simple metronome 21
7. What is a resistor? 24
8. Waves – Part 1 27
9. A beat-frequency oscillator 31
10. What is a capacitor? 34
11. Waves – Part 2 38
12. An LED flasher 41
13. Waves – Part 3 44
14. Choosing a switch 46
15. An aerial tuning unit for a receiver 49
16. A simple 2 m receiver preamplifier 52
17. Receiving aerials for amateur radio 54
18. The Colt 80 m receiver – Part 1 58
19. A crystal radio receiver 62
20. The varactor (or varicap) diode 64
21. A portable radio for medium waves 65
22. The Colt 80 m receiver – Part 2 70
23. A simple transistor tester 73
24. An introduction to transmitters 77
25. The Colt 80 m receiver – Part 3 81
26. A two-way Morse practice system 88
27. The Colt 80 m receiver – Part 4 91
28. A simple crystal set 95
29. A crystal calibrator 100
30. A simple short-wave receiver – Part 1 104
31. A fruit-powered medium-wave radio 106
32. A capacitance bridge 109
33. A simple short-wave receiver – Part 2 113
34. A basic continuity tester 117
35. A charger for NiCad batteries 119
36. An 80 metre crystal-controlled CW transmitter 123
37. A solar-powered MW radio 129
38. A receiver for the 7 MHz amateur band 133
39. Diodes for protection 137
40. An RF signal probe 140
41. An RF changeover circuit 142
42. A low-light indicator 146
43. A J-pole aerial for 50 MHz 149
44. Measuring light intensity – the photometer 153
45. A 70 cm Quad loop aerial 156
46. A UHF field strength meter 160
47. Christmas tree LEDs 162
48. An audio signal injector 166
49. Standing waves 168
50. A standing-wave indicator for HF 170
51. A moisture meter 174
52. Simple aerials 177
53. A breadboard 80 cm CW transmitter 182
54. A 7-element low-pass filter for transmitters 186
55. Radio-frequency mixing explained 189
56. A voltage monitor for a 12 V power supply 192
57. A 1750 Hz toneburst for repeater access 196
58. A circuit for flashing LEDs 201
59. Digital logic circuits 205
60. A resistive SWR indicator 210
61. An audio filter for CW 213
62. An electronic die 215
63. The absorption wavemeter 222
64. An HF absorption wavemeter 224
65. A vertical aerial for 70 cm 228
66. A UHF corner reflector aerial 230
67. A switched dummy load 234
68. A simple Morse oscillator 238
69. A bipolar transistor tester 240
70. The ‘Yearling’ 20 m receiver 245
71. Adding the 80 metre band to the Yearling receiver 251
72. How the Yearling works 255
73. A field strength meter 258
74. Preselector for a short-wave receiver 261
75. An audible continuity tester 265
76. An experimental 70 cm rhombic aerial 268
77. Water level alarm 272
78. A delta loop for 20 metres 275
79. A simple desk microphone 279
80. Morse oscillator 284
81. A simple 6 m beam 287
82. An integrated circuit amplifier 291
83. A novice ATU 293
84. CW QRP transmitter for 80 metres 297
85. An audio booster for your hand-held 303
86. A grid dip oscillator 306
87. A CW transmitter for 160 to 20 metres 312
88. Matching the end-fed random-wire aerial 315